Methods for detecting and determining a leak in a tank device are disclosed in the prior art. Thus, for example, DE 102 54 986 A1 discloses a method for tank leak diagnosis in a tank ventilation device in which the pressure increase in the tank ventilation device is computed based on the outgassing or evaporating fuel by means of the mass balance and is also considered in the determination of a leak, for tank leak diagnosis the tank ventilation device being “evacuated,” so that a negative pressure is formed.
Current methods for detecting or determining a leak while the engine is running, i.e., during operation of an internal combustion engine which has a tank device, due to physical boundary conditions are not able to reliably detect a leak of 0.5 mm. In these cases a downstream diagnosis is necessary after “engine-off”, that is, with the internal combustion engine turned off, which is more sensitive than required and leads to a high closed-circuit current load in the vehicle.
It is therefore the object of the invention to reliably detect a leak of up to 0.5 mm in size, the size of the leak being defined by the diameter (for example, d=0.5 mm).